Tracing mechanism for duplicating milling machines



G. SCHLAPP Nov. 21,1967

TRACING MECHANISM FOR DUPLICATING MILLING MACH INES 8 Sheets-Sheet 1 Filed May 27, 1966 Invenior:

GEORG SCHLHFJP G. SCHLAPP Nov. 21, 1967 TRACING MECHANISM FOR DUPLICATING MILLING MACHINES 8 Sheets-Sheet 2 Filed May 27, 1966 lnven/or:

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GEORG SCHLFIPP I G. SCHLAPP Nov. 21, 1967 TRACING MECHANISM FOR DUPLICATING MILLING MACHINES 8 Sheets-Sheet 4 Filed May 27, 1966 lnvenfar:

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TRACING MECHANISM FOR DUPLICATING MILLING MACHINES Filed May 27, 1966 I s Sheets-Sheet s Fig.12

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GEORGQSCHLHPD Nov. 21, 1967 G. SCHLAPP 3,353,449

T RACING MECHANISM FOR DUPLICATING MILLING MACHINES I Filed May 27, 1966 8 Shets-Sheet v Fig.1

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' HTTORNEYS v United States Patent 3,353,449 TRACING MECHANISM FOR DUPLICATING MILLING MACHINES Georg Schlapp, Langen, near Frankfurt am Main, Germany, assignor to Nassovia Werkzeugmaschinenfabrik G.m.h.H., Frankfurt am Main, Germany Filed May 27, 1966, Ser. No. 553,572 Claims priority, application Germany, May 28, 1965, N 26,799 5 Claims. (Cl. 90-62) This invention relates to a key-operated and controlled duplicating machine tool and in particular to an electrohydraulically acting tracing mechanism for a duplicating machine which operates in the manner of an advanced controlled machine.

This invention applies to duplicating machines of the type disclosed in the patent to Kohl, No. 3,241,455.

The object of this invention is to produce an advance control mechanism in which the drive to the advance control mechanism becomes always only effective when the pattern contour changes, and further that a certain angle is maintained between the direction of the advance force and the contact tangent between the tracer and pattern.

In this invention, a measuring ring or ball is mounted on the tracer and the measuring head is rotatably driven around the axis of the ring or ball, said head having two pulse transmitters adapted to contact the measuring ring or ball. Pulses from the transmitters, by means of an electronic guiding system, start the rotation of the measuring head in the sense of the advance control either clockwise or counterclockwise as soon as the pattern contour deviates from the contact tangent. Thus the measuring head does not rotate as soon as the contact tangent between the tracer and pattern coincides with the pattern contour. This assures that the measuring head is rotated merely during a change in contour as, for example, a deviation of the contact tangent from the pattern contour and remains stopped otherwise which increases its life span. Also, this electrically operated advance control mechanism presents, in connection with the hydraulic control elements actuated by parallel outward movement of the tracer, the currently most advanced development for controlling the tracer to obtain the highest degree of duplicating accuracy.

The pulse transmitters are composed of three electrical contacts mounted on the front side of the measuring head and equally spaced on a circular arc. The center electrical contact is joined to the control apparatus and produces the advance force and lies diametrically opposite a spring-pressed member. The adjoining electrical contacts are also joined to the control apparatus. The pressure member is composed of a one-sided centralizing leg which bears against the measuring ring or ball in such a way that the end of the leg transmitting the advance force pushes the ring or ball to an eccentric position and against the measuring head. This, in turn, pushes the tracer against the pattern. When the contact tangent between the tracer and pattern coincides with the pattern contour, the measuring ring or ball is always closed with the center and one adjoining electrical contact. When the contact tangent deviates from the pattern contour, the ring or ball closes with the middle electrical contact or one of the adjoining contacts or is open with respect to all electrical contacts. Preferably, the electrical contacts are arranged relative to one another and to the pressure member so that when the contact tangent deviates from the pattern contour the following relations between the electrical contacts and the measuring ring or ball can become possible.

An electrical contact between the measuring ball or ring and the center electrical contact takes place when the tracer tends to leave the pattern, a contact between the measuring ring or ball and one of the adjoining electrical contacts takes place when slopes or gradients are being traced which lie above the built-in check point or self-stopping of the tracer, and no contact between the measuring ball or ring in any of the electrical contacts occurs when the tracer is forced back by the pattern contour relative to its direction of movement. The electrical contacts are mounted on the measuring head which is driven by a motor and which head is like a ring and surrounds a measuring element such as a ball which is positioned on the end of the tracer, or can be a disc-like measuring head which surrounds a measuring ring mounted on the end of the tracer rod. The electrical contacts can be in the form of rollers which are insulated from one another. In using a disc-like measuring head surrounded by the measuring ring to bring the advance control mechanism into one of the three directions of movement in the system of coordinates and, if desired, to any angle lying between the coordinate axes, the measuring ring can be pivoted and locked around an axis extending at right angles to the tracer axis and mounted in a bifurcated member enclosed on the end of the tracer.

The means by which the objects of the invention are obtained are disclosed more fully with reference to the accompanying drawings, in which:

FIGURE 1 is a front view partially in section of the measuring head of this invention engaging the end of a tracer which is following a pattern;

FIGURE 2 is a cross-sectional view taken on the line II-II of FIGURE 1 with the measuring head rotated to the left;

FIGURE 3 is a view similar to FIGURE 1 of a modification using electrical contact segments;

FIGURE 4 is a cross-sectional view taken on the line IV-IV of FIGURE 3 with the measuring head rotated 120 to the left;

FIGURE 5 is a view similar to FIGURE 1 showing a modification in which the measuring head is in the form of a disc having electrical contact rollers;

FIGURE 6 is a cross-sectional view on the line VIVI of FIGURE 5 with the measuring head rotated 60 to the right;

FIGURE 7 is a view similar to FIGURE 5 and showin g a modification in which the measuring head disc contains electrical contact segments;

FIGURE 8 is a cross-sectional view taken on the line VIII-VIII of FIGURE 7 with the measuring head rotated 60 to the right;

FIGURE 9 is a schematic circuit diagram of the control system for the advance control mechanism; and

FIGURES 10 to 18, inclusive, are diagrammatic views showing the positions of the measuring head with regard to various pattern contours in a line milling process.

The same reference characters are used to represent identical parts in the various figures.

FIGURES 1 to 8 show an advance control for a duplicating machine tool in which the tracer housing 1 contains fork levers 2 and 2' joined to the tracer rod 3 which holds the tracing pin 4. Levers 2 and 2 permit the tracer rod 3 to move parallel to itself in three space planes. Through the levers 2 and 2' rod 3 communicates with slide valves 5, 6 and 7 in such a way that the valves, upon outward movement of the rod 3, actuate pistons for mov ing the workpiece sleds in a direction which corresponds to the outward movement of the tracer. The outward movement distance of the tracer, and thus the movement of the hydraulic control valves, corresponds to the velocity of the forward movement. The advance control mechanism is rotatably mounted in a circular guide groove 8.

The advance control mechanism has a base 9 rotatable in groove 8 and supports a cover 10 which is pivotally supported by pins 11 on an axis which lies at right angles to the longitudinal axis of rod 3 and can be swung to and fastened in any position in the space coordinates. In FIGURES 1 to 4, the advance control mechanism consists essentially of a measuring ball 13 fastened to the upper end of rod 3 and which extends through an opening 12 in the cover 10. A shaft 15 is rotatably driven by a motor 16 for turning the measuring head. This head, in FIGURES 1 and 2, carries three electrical contact rollers 17, 18 and 19 which are mounted on the front end of the measuring head and are equally spaced on a circular arc. The center plane of the electrical contact rollers extends through the center of measuring ball 13 and lies on the longitudinal axis of rod 3. In FIGURES 3 and 4, electrical contact segments 20, 21 and 22 are used instead of the rollers of FIGURES l and 2. Diametrically opposite roller 18 or segment 21 are two pressure rollers 23 and 24 supporting a centering leg 25 and pivotable around a fulcrum 26 and annular lever 27. A spring 28 produces the advance force and extends between the cover 10 and the free end of lever 27. Centering leg 25 bears constantly against ball 13 to force the ball constantly into an eccentric position within the measuring head.

The amount of the eccentricity in this instance corresponds to the distance of the forward movement of the tracer with regard to the pattern. The electrical contact rollers 17, 19 or the segments 20, 22 are connected by a common electrical line 29 with control apparatus 30 while roller 18 or segment 21 has a separate electrical line 31 leading to control apparatus 30. The control voltages or pulses are produced from rollers 17, 19 or segments 20, 22 through a collecting ring 32 mounted on the circumference of the measuring head and from there to sliding contact 33 to line 29. From roller 18 or segment 21, the current is transmitted through a second collecting ring 34 connected to the roller 18 by wire 34' and through a sliding contact 35 joined to line 31.

FIGURES 5, 6, 7 and 8 show an advance control mechanism in which a measuring ring 36 is used instead of a ball and the measuring head is in the form of a disc 37. The measuring ring 36 is tiltably supported on a bifurcated member 38 by means of pins 39, with the member 38 rotatably supported by a pin 40 journalled in roller bearings 41 on the upper end of the tracer rod. Ring 36 can thus be turned horizontally and also tilted to any desired position. Measuring head 37 contains three electrical contact rollers in a manner similar to FIGURE 1 and the roller 18 is again diametrically opposite centering leg 25 supported by the pressure rollers 23 and 24. Leg 25 is constantly forced against the measuring ring 36 by lever 27 pressed by spring 28. The measuring ring is brought into an eccentric position with respect to the measuring head by an advancing distance x. Rollers 17 and 19 are joined to collecting ring 32 on the outer circumference of the measuring head and electrically connected to sliding contact 33 and line 29 which is common to both and to the control apparatus 30. Roller 19 is electrically connected to collecting ring 34 and to the control apparatus through sliding contact 35 and line 31.

FIGURES 7 and 8 show a modification of the mechanism of FIGURES and 6 which is analogous to FIG- URES 2 and 3. The electrical contact rollers are replaced by contact segments 20, 21 and 22 which are electrically connected to the control apparatus as described for FIG- URES 6 and 7.

FIGURE 9 is a schematic circuit diagram for the control of the advance control mechanism by the control apparatus 30. The same reference numerals for the electrical contacts and lines are used as shown in FIGURES 1 to 8. The reference numerals in parenthesis are those of the corresponding parts of FIGURES 5 to 8. With a constant low voltage of about 24 volts, measuring ball 13 or ring 37 represent the stationary mass of the machine.

The counter electrical contact rollers 17, 18 and 19 or segments 20, 21 and 22 are openable or closable with the measuring ball 13 or ring 37 as determined by the pattern contour or thus the outward movement of the tracer. Contacts 17 (20) and 19 (22) are joined to a common line 29 which leads through a relay Y to the other polarity while contact 18 (21) is connected by line 31 through relay Z to the same polarity. Contacts Y1, Y2 of the relay Y and Z1, Z2, Z3 and Z4 of the relay Z are electrically joined to the motor 16 for electrically driving the measuring head and functions as follows:

It is assumed that the measuring head electrical contacts as shown in the schematic circuit are open, that is contacts Y1, Y2 and Z2 and Z3 are closed and contacts Z1 and Z4 are open. Current thus flows by way of contact Z2, motor 16 and contact Z3 to the other polarity and in this instance the motor rotates counterclockwise. This setup corresponds on one hand to the idling position of the tracer, that is the tracer has no contact with the pattern and on the other hand, a position in which the tracer is forced back by the contour of the pattern relative to its direction of movement, such as has been approximately shown in FIGURES 4 and 5. In the following paragraph, the further effect of the control apparatus and the advance control mechanism will be described for various possible outward movements of the tracer as shown in FIGURES 10 to 1-8 and this includes the various switching positions of the measuring head.

After the tracing rod has been mechanically or manually spotted on the pattern, as shown in FIGURE 10, the measuring ball 13 is forced aaginst the two electrical contact rollers 17 and 18 by the advance force produced by roller 23 of the centering leg.

The advance force acting on the pattern in the direction of the arrow thereby forms an acute angle of about 30 with the angle of contact between the tracer and the pattern. The bisector of the angle enclosed between two electrical contacts such as rollers 17 and 18 which exists during inoperative position of the measuring head in touching contact with the measuring ball lies always parallel to the contact tangent between the tracer and the pattern. By closing the contacts, the two relays Y and Z are actuated so that contacts Y1, Y2, Z2 and Z3 are opened and contacts Z1 and Z4 are closed. The circuit to motor 16 is thus opened and the motor is stopped so that no rotary movement of the measuring head can take place. The tracing rod moves because of the small outward movement of the advance piston and effects a movement along the surface of the pattern in FIGURE 10 from left to right. As soon as the tracer reaches the corner as shown in FIGURE 11, the rod drops and ball 13 is brought under the effect of the advance force by means of the centering leg and put into a position in which the contact between ball 13 (36) and contact 17 (20) is open and only the contact 18 is closed with ball 13. Both rollers 23 and 24 of the centering leg now bear against ball 13 and force the same against contact 18. Because contact 17 is open with ball 13, the working contacts Y1 and Y2 of relay Y are again closed and contacts Z1, Z4 and Z2, Z3 remain closed and/or open. Current then flows by way of Y1, Z1 to the other control line of the motor and by way of Z4, Z2 back to the pole. The motor therefore rotates to the right. This means that the measuring head is rotated in the direction of the arrow as shown in FIGURE 11 until the rotating direction of the advance force which is the direction of the arrow shown adjacent the pattern has again restored the lost ratio of the 30 angle between the advance force direction and the contact tangent. This is achieved as soon as the centering leg 25 has forced the ball 13 and thus the tracer in the position shown in FIGURE 12 in which ball 13 is forced against contact rollers 17 and 18 by means of roller 23 until renewed closed contact occurs between the contact 17 (20), 18 (21) and 13 (36) which results in the renewed actuation of relay Y and thus an opening of the contacts Y1 and Y2 and therefore stoppage of motor 16. The tracing rod in FIGURE 12 now moves downwardly. If, during this downward movement, it hits again on the pattern contour, which now runs horizontally (see FIGURE 13), it is forced back against its direction of movement by the distance advanced, which is the amount of the eccentricity of the measuring ball to the measuring head. All contacts 17, 1S and 19 have now become open with respect to ball 13. The functions of the control have heretofore been described; they correspond to the switching positions shown in FIGURE 9. The measuring head is thus driven counterclockwise and momentarily takes a standstill position as shown in FIGURE 10, and this continues until the tracing rod reaches the slanting or inclined pattern contour shown in FIGURE 14. At this point, its outward movement is vertical so that the contact between ball 13 (36) and the center roller 18 (21) is again open and only contact 17 is closed with ball 13. Relay contacts Z1, Z4 of relay Z are again open and the contacts Z2 and Z3 are closed. Motor 16 again drives the measuring head counterclockwise until the contact tangent of approximately 30 has been again formed for the direction of the forward force as shown in FIGURE 15. Otherwise, expressed, until the bisector of the angle formed by the contacts 17 and 18 to the center of the measuring head is parallel to the pattern contour. The measuring ball and tracer are again forced by the roller 23 against the measuring head and the pattern and the contacts 17 and 18 are closed with ball 13. This again actuates relay Z3 to close contacts Z1 and Z4 and open contacts Z2 and Z3. The motor circuit is thus opened and the motor stopped. The tracing rod traces the inclined pattern contour shown in FIG- URE 15. In the tracing position of FIGURE 16, the rod is again moved outward by the vertical contour, this outward movement being relative to its direction of movement and ball 13 is forced back to its center position, that is concentric to the measuring head. Contacts 17 and 18 are now open with respect to ball 13 and the switching functions of the relay occur as described for FIGURE 13. The measuring head is driven counterclockwise until the direction of the advance control forms again the prescribed angle With respect to the contact tangent. It is at this moment that the ball 13 is forced by the advance force and by roller 23 of the centering leg into the position of FIGURE 17, that is closing contacts 17 and 18.

The control procedures now started in the control apparatus are similar to those for FIGURES 10, 12 and 15. The current motor is open and the motor stopped. The tracing pin traces the vertical contour upwardly and at the moment of its outward movement at the upper edge of the pattern in FIGURE 18 the contact tangent changes and ball 13 is forced under the middle effect of the centering leg and simultaneous pressure of rollers 23 and 24 against contact 18 so that the same control procedure is started as described for FIGURE 11. Motor 16 drives the measuring head clockwise until the position of the tracer has again achieved the position shown in FIGURE 10. The tracer then moves as in FIGURE to the right. By means of a change, motor combination 42 (FIGURE 9) which can be controlled by a limit switch arranged at the end of the working sled, it is possible that the direction of rotation of the machine can be alternated. It is clear that resistors or tubes or any other equivalent means can be used for the electrical control elements of the control apparatus instead of relays.

Having now described the means by which the objects of the invention are obtained,

I claim:

1. In a duplicating machine tool having a tracer adapted to follow a pattern, a measuring element mounted on said tracer, an advance control mechanism having a measuring head rotatably engageable with said element for forcing said tracer in constant engagement with the pattern and automatically determining the advance direction as a function of the contact tangent between the tracer and pattern, and means in said measuring head activated by engagement of said head with said element for transmitting two impulses to an electronic control for rotating said head clockwise or counterclockwise as soon as the pattern contour deviates from the contact tangent and for stopping rotation when the contact tangent coincides with the pattern contour.

2. In a tool as in claim 1, said means comprising three equally spaced electrical contacts mounted on said head and lying on a circular are, a spring-pressed member mounted on said head diametrically opposite the center electrical contact and bearing on said element, means electrically connecting the center electrical contact to the advance control mechanism for producing the advance force, means electrically connecting the two electrical contacts adjoining the center contact with the advance control mechanism, and said spring-pressed member holding said element in eccentric position with respect to said head to close the center and one adjoining electrical contact when the contact tangent coincides with the pattern contour, and opening at least the center electrical contact when the contact tangent deviates from the pattern contour.

3. In a tool as in claim 2, said measuring element being closed with said center electrical contact when said tracer tends to leave the pattern, said measuring element being closed with one of said adjoining electrical contacts when slopes are traced on the pattern which lie above the selfstopping of the tracer, and said measuring element being open with respect to said electrical contacts when said tracer is pushed back by the pattern contour relative to its direction of movement.

4. In a tool as in claim 3, said electrical contacts comprising rollers.

5. In a tool as in claim 4, said measuring element com prising a bifurcated member turnably mounted on said tracer, and a measuring ring pivotally secured to said member on an axis at a right angle to said tracer and engageable wtih said measuring head.

References Cited UNITED STATES PATENTS GERALD A. DOST, Primlary Examiner. 

1. IN A DUPLICATING MACHINE TOOL HAVING A TRACER ADAPTED TO FOLLOW A PATTERN, A MEASURING ELEMENT MOUNTED ON SAID TRACER, AN ADVANCE CONTROL MECHANISM HAVING A MEASURING HEAD ROTATABLY ENGAGEABLE WITH SAID ELEMENT FOR FORCING SAID TRACER IN CONSTANT ENGAGEMENT WITH THE PATTERN AND AUTOMATICALLY DETERMINING THE ADVANCE DIRECTION AS A FUNCTION OF THE CONTACT TANGENT BETWEEN THE TRACER AND PATTERN, AND MEANS IN SAID MEASURING HEAD ACTIVATED BY 